I use a micro adjusting dual action stainless steel truss rod with the flat bar strap on top. It’s a dual action truss rod with micro adjustment capabilities. I trap the rod by putting a piece of wood directly over the adjusting nut, then gluing the spline over this (then the fingerboard). This isolates that top flat bar and exploits its stiffness to further mitigate neck compression. This multiplies the rod's stiffness.